<!DOCTYPE html>
<html>

<head>
	<meta charset="utf-8">
	<title>回到顶部效果</title>
	<link rel="stylesheet" href="./style.css">
</head>

<body>
	<ul>
		<li><img src="img/1.jpg" alt="图片加载失败!"></li>
		<li><img src="img/2.jpg" alt="图片加载失败!"></li>
		<li><img src="img/3.jpg" alt="图片加载失败!"></li>
		<li><img src="img/4.jpg" alt="图片加载失败!"></li>
	</ul>
	<button>回到顶部</button>

	<script src="./index.js"></script>
</body>

</html>